A Center-of-Gravity-Based Approach to Estimate Slow Power and Frequency Variations

A novel approach based on the notion of center-of-gravity (COG) dynamics in mechanics is used to estimate local and global power system's frequency behavior. In this framework, the power system dynamic behavior is represented by an equivalent model in which the geographical areas interact with the COG through fictitious interconnectors from which the inherent dynamics of power frequency transients is explained using fundamental physics principles. The relationship between the frequency of the COG and the motion of local centers of angle is determined and expressions to compute local frequency deviations following major disturbances are derived. Detailed simulation results on three test power systems are used to demonstrate the accuracy and flexibility of the proposed method under both, N-1 and N-2 contingencies.